Mapping JPA entity relationships - jpa

Question

I would like some advice on how to best layout my JPA entity classes. Suppose I have 2 tables I would like to model as entities, user and role.
Create Table users(user_id primary key,
role_id integer not null )
Create table role(role_id primary key,
description text,
)
I create the following two JPA Entities:
#Entity
#Table(name="users")
#Access(AccessType.PROPERTY)
public class User implements Serializable {
private Long userId;
private Long roleId;
private Role role;
#Column(name = "user_id")
#Id
public Long getUserId() {}
#Column(name = "role_id")
public Long getRoleId() {}
#ManyToOne()
JoinColumn(name="role_id")
public Role getRole() {}
}
Role Entity:
#Entity
#Table(name="Role")
#Access(AccessType.PROPERTY)
public class Role implements Serializable {
private String description;
private Long roleId;
#Column(name = "role_id")
#Id
public Long getRoleId() {}
#Column(name = "description")
public Long getDescrition(){}
#ManyToOne()
#JoinColumn(name="role_id")
public Role getRole() {}
}
Would the correct way to model this relationship be as above, or would I drop the private Long roleId; in Users? Any advice welcomed.
When I map it this way, I receive the following error:
org.hibernate.MappingException: Repeated column in mapping for entity:

Answer 1

Yes, you would drop the private Long roleId mapping when you have a #ManyToOne on the same column.
As the error implies, you can only map each column in an #Entity once. Since role_id is the #JoinColumn for the #ManyToOne reference, you cannot also map it as a property.
You can, however, add a convenience method to return the role ID, like
public Long getRoleId() {
return role.getId();
}